@SugarCoats
We’re both middle aged. It was caused by a medical injury during a near death illness.
That poor man, I'm so sorry.
I can understand why some posters are being very blunt and to the point but it's easy for somebody to say "just dump him" when they don't actually know him, know you or know about the history you share (alot of which sounds positive and supportive)
However I do agree that you're going to need to bite the bullet with regards to telling him how much this is impacting you.
I can relate somewhat albeit on a lower scale. My OH is on the autistic spectrum, aspergers as it was previously known, and as such he has some sensory issues that make brushing his teeth very difficult for him.
His teeth look fine, miraculously, but when he hasn't brushed them properly for a while his breath isn't the best and it is quite off-putting when it comes to intimacy.
Like your partner, he's terribly sensitive and embarrassed about it so bringing it up is tricky and awkward but had to be done and after some unavoidable embarrassment he went out and bought himself some medicated mouthwash and a new electric toothbrush. I gently remind him after I've done mine.
As he's fastidious about all other aspects of his personal hygiene its not something I would throw the relationship away over - especially given the fact there is a medical/neurological reason for it and he's otherwise a great partner/father (I realise you have said you don't see yours romantically)
The age old saying "you have to be cruel to be kind" is very apt here and I do think you need to have the conversation for both of your sakes. I would tell him that you love and care about him and as such you must insist he asks for help and insists he receives some because he shouldn't have to live like this and neither should you.
A PP had a good suggestion about him disposing of the pads in nappy sacks. They're completely smell proof which I can testify to, having three small DC who are all in nappies.